Feline superfecundation occurs when a litter of kittens has more than one father. Tomcats squabble over a female in heat and most females promiscuously allow one male after another to mate with her. Thus, all her admirers who have been fighting over her have their opportunity. Her reproductive tract contains the sperm of several males and chance dictates which individual’s sperm fertilises each of her shed eggs.
This results in a litter of kittens with a variety of appearances. This might happen anyway if only one male had fertilised the eggs, because of genetic reasons. However, a great variation in coat types among the litter may instead be the result of different fathers.
Wild cats live in lower densities, sometimes very low densities which limits this sort of behaviour, so it is essentially a domestic cat phenomenon. It is more likely to occur in urban stray cats where colonies have reduced home ranges and where a female in heat attracts a lot of tomcats.
With ‘superfetation’ it is another example of the feline’s enhanced breeding capabilities. The act of copulation takes around five seconds with ejaculation occurring immediately after the male has entered the female. They rest for about 20 minutes and recommence. This is repeated approximately seven times at which point the male has had enough.
The next question is whether superfecundation happens in humans? And apparently it does but very rarely. It is known as heteropaternal superfecundation. It’s not known how often it occurs apparently. This is because people don’t request DNA testing when suspicious. Sometimes they do. One study estimated that it might happen as often as one in 420 births in the US.
